Secondary cells have been employed everywhere in the world, and in order to give the cell high energy density and high power, electrodes of secondary cells have been intensely studied. For example, there have been proposed, as anode active materials, transition metal oxides or transition metal chalcogenates (e.g. TiS.sub.2, MoS.sub.2, CoO.sub.2, V.sub.2 O.sub.5, FeS.sub.2, NbS.sub.2, ZrS.sub.2, NiPS.sub.3, VSe.sub.2, MnO.sub.2 etc.), heat polymerizates of organic materials (e.g. one-dimension graphitizate, fluorinated carbon, graphite etc.) and electroconductive polymers (e.g. polyacetylene, polypyrrole, polyaniline, polyazulene etc.). Also, non-hydrogen cells or capacitors using lithium, lithium alloy or graphite as cathode are proposed, because they give the cells light weight and high energy density in comparison with conventional cells.
However, when lithium metal is used as cathode, the lithium metal dissolves into electrolyte as lithium ion upon discharging and the lithium ion upon charging in turn deposits on the cathode. When this charge and discharge cycle is repeated many times, the deposited lithium metal grows as dendrite form and may reach the anode to shortcut. The shortcut often reduces the charge and discharge cycle. In order to overcome the problem, many solutions have been proposed.
For example, Japanese Kokai Publication 62-243247 suggests that a lithium metal plate which is sandwiched between two aluminum plates is used as cathode for the secondary cells. This reduces the formation of dendrite, but the surface area of the cathode reduces and the charge and discharge capacity also reduces. Japanese Kokai Publication 1-63268 discloses that, in order to increase the surface area of the cathode, porous Li-Al alloy with a pore size of 5.mu. or more is used as cathode. The pore size of the porous Li-Al alloy, however, is large enough to have poor mechanical strength and the alloy easily breaks when mounting into the cells.
It is also proposed that lithium is doped into a carbonaceous material to form a cathode. For example, Japanese Kokai Publications 62-122066 and 62-90863 suggest carbonaceous material which is obtained by carbonizing organic material. The carbonaceous material is doped with lithium to form an electrode which, however, does not have enough dope amount and has poor performance. In order to improve the above problems, Japanese Kokai Publication 3-13710 provides a method for producing a cathode electrode wherein a carbonaceous material which is produced by carbonizing furan resin to which a phosphorus compound is added, is powdered and dispersed in an organic solvent together with poly(vinylidene fluoride) powder, which is then coated on stainless steel with removing the organic solvent and compression-molded. The resulting electrode, however, does not have sufficient performance.
Japanese Kokai Publication 61-277165 discloses a graphite which is obtained by heat-treating aromatic polyimide at a temperature of 2,000.degree. to 8,500.degree. C. in inert atmosphere. The graphite is suggested for use as at least one of the electrodes of a secondary cell. The graphite, however, has poor charge-discharge capacity and coulomb efficiency.